Raid Array Transformation in a Pooled Storage System

1. A system, comprising: an extent reserving component adapted for reserving one or more extents in a storage pool; a data migrating component adapted for: reading data from a first portion of an in-use redundant array of independent disks (RAID), wherein the first portion of the in-use RAID is arranged according to a first array configuration having at least a first parameter; using the one or more reserved extents in the storage pool to store at least a first portion of the data for writing to the in-use RAID; using one or more free extents in the storage pool or in the in-use RAID to store at least a second portion of the data for writing to the in-use RAID; and writing the data to a second portion of the in-use RAID, wherein the second portion of the in-use RAID is arranged according to a second array configuration having at least a second parameter; a first I/O component adapted for performing one or more first I/O operations according to the first array configuration, wherein the one or more first I/O operations are performed on the data before the data is read by the data migrating component; and a second I/O component adapted for performing one or more second I/O operations according to the second array configuration, wherein the second I/O operations are performed on the data after the data is read by the data migrating component, wherein a logical data structure of the in-use RAID is preserved.

2. The system as recited in claim 1 , wherein the first and second parameters comprise at least one of: a number of disks, a disk storage capacity, an array storage capacity, and a RAID level.

3. The system as recited in claim 1 , wherein the second array configuration is characterized by having a different number of disks than the first array configuration, the first array configuration having a plurality of disks in at least two drives, the second array configuration having a plurality of disks in at least two drives.

4. The system as recited in claim 1 , wherein the data migrating component is further adapted for determining that the one or more free extents are needed for data migration based at least in part on whether the one or more reserved extents are currently being used.

5. The system as recited in claim 1 , further comprising logic configured to instantiate first and second views of drives comprising the RAID array, wherein the first view utilizes the parameters of the first array configuration, and wherein the second view utilizes the parameters of the second array configuration.

6. The system as recited in claim 1 , wherein the RAID comprises: a first plurality of disks having a first capacity; and a second plurality of disks having a second capacity, wherein the first array configuration uses the first plurality of disks and the second plurality of disks, and wherein the second array configuration uses either the first plurality of disks or the second plurality of disks.

7. The system as recited in claim 1 , wherein the first portion of the in-use RAID is made available for further data migration after the data is written to the at least one reserved extent and the at least one free extent.

8. The system as recited in claim 1 , wherein the second array configuration is characterized by having a different number of disks than the first array configuration, wherein the second array configuration is characterized by having a different storage capacity than the first array configuration, wherein the second array configuration is characterized by having a different RAID level than a RAID level of the first array configuration, wherein the RAID comprises: a first plurality of disks having a first capacity; and a second plurality of disks having a second capacity, wherein the first array configuration uses the first plurality of disks and the second plurality of disks, and wherein the second array configuration uses either the first plurality of disks or the second plurality of disks.

9. A method, comprising: reserving one or more extents in a storage pool; reading data from a first portion of an in-use redundant array of independent disks (RAID), wherein the first portion of the in-use RAID is arranged according to a first array configuration having at least a first parameter; using the one or more reserved extents in the storage pool to store at least a first portion of the data for writing to the in-use RAID; using one or more free extents in the storage pool and/or in the in-use RAID to store at least a second portion of the data for writing to the in-use RAID; writing the data to a second portion of the in-use RAID, wherein the second portion of the in-use RAID is arranged according to a second array configuration having at least a second parameter that is different than the first parameter; performing one or more first I/O operations according to the first array configuration, wherein the one or more first I/O operations are performed on the data before the data is read by the data migrating component; and performing one or more second I/O operations according to the second array configuration, wherein the second I/O operations are performed on the data after the data is written to the second portion of the in-use RAID, wherein a logical data structure of the in-use RAID is preserved.

10. The method as recited in claim 9 , wherein the first and second parameters comprise at least one of: a number of disks, a disk storage capacity, an array storage capacity, and a RAID level.

11. The method as recited in claim 9 , wherein the second array configuration is characterized by having a different number of disks than the first array configuration.

12. The method as recited in claim 9 , wherein the first portion of the in-use RAID is made available for further data migration after the data is written to the at least one reserved extent and the at least one free extent.

13. The method as recited in claim 9 , determining that the one or more free extents are needed for data migration based at least in part on whether the one or more reserved extents are currently being used.

14. The method as recited in claim 9 , further comprising instantiating first and second views of drives comprising the RAID array, wherein the first view utilizes the parameters of the first array configuration, and wherein the second view utilizes the parameters of the second array configuration.

15. A computer program product, the computer program product comprising a non-transitory computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising: computer readable program code configured to reserve one or more extents in a storage pool; computer readable program code configured to read data from a first portion of an in-use redundant array of independent disks (RAID), wherein the first portion of the in-use RAID is arranged according to a first array configuration having at least a first parameter; computer readable program code configured to use the one or more reserved extents in the storage pool to store at least a first portion of the data for writing to the in-use RAID; computer readable program code configured to determine that at least one more extent than the one or more reserved extents is needed for data migration; computer readable program code configured to locate one or more free extents; computer readable program code configured to use the one or more free extents in the storage pool and/or in the in-use RAID to store at least a second portion of the data for writing to the in-use RAID; computer readable program code configured to write the data to a second portion of the in-use RAID, wherein the second portion of the in-use RAID is arranged according to a second array configuration having at least a second parameter that is different than the first parameter; computer readable program code configured to perform one or more first I/O operations according to the first array configuration, wherein the one or more first I/O operations are performed on the data before the data is read by the data migrating component; and computer readable program code configured to perform one or more second I/O operations according to the second array configuration, wherein the second I/O operations are performed on the data after the data is written to the second portion of the in-use RAID, wherein a logical data structure of the in-use RAID is preserved.

16. The computer program product as recited in claim 15 , wherein the first and second parameters comprise at least one of: a number of disks, a disk storage capacity, an array storage capacity, and a RAID level.

17. The computer program product as recited in claim 15 , further comprising computer readable program code configured to determine that the one or more free extents are needed for data migration based at least in part on whether the one or more reserved extents are currently being used.

18. The computer program product as recited in claim 15 , further comprising computer readable program code configured to instantiate first and second views of drives comprising the RAID array, wherein the first view utilizes the parameters of the first array configuration, and wherein the second view utilizes the parameters of the second array configuration.

19. The computer program product as recited in claim 15 , wherein the first portion of the in-use RAID is made available for further data migration after the data is written to the at least one reserved extent and the at least one free extent.

20. The computer program product as recited in claim 15 , wherein the second array configuration is characterized by having a different number of disks than the first array configuration, wherein the second array configuration is characterized by having a different storage capacity than the first array configuration, wherein the second array configuration is characterized by having a different RAID level than a RAID level of the first array configuration.